A: The engineers who designed the solid rocket booster [SRB] engines for the US Space Shuttle wanted to build them bigger, but the SRBs had to be shipped by train from their Thiokol factory in Utah, through a mountain tunnel to reach the Florida launch site.

US railroads were built by English expatriates (to explain why US built locomotives can operate on English rails and visa versa.)

The companies that built the English railroad system were the same companies that built the original London tramways.

The jigs used to build the tramways were the same jigs that had been used to build wagons.  English and American wagons have the same wheelbase.

Wagon wheel axels were built to fit inside the ruts that Roman Chariots had swathed all across Europe and England.  Any other measurement would have snapped the wheels completely off.  Those pathways became modern English roads.

Roman war chariots were made just wide enough to accommodate the back end of two war horses and that measurement was 4' 8.5".  Roman manufacturers built all chariots alike so that parts could be salvaged from wrecked chariots, not unlike modern scavenging techniques.

So, it's no coinsidence that US and UK railway systems have the same rail gauge as the wheelbase of a 2,000-year-old Roman chariot and that the Space Shuttle was designed to accomodate a horse's ass.

Any Questions?